2-SHANKS
“Red Haired” Shanks is Luffy’s role model and the man that our main protagonist wants to surpass one day. It makes sense in the series that Shanks is powerful because he is that character that the main protagonist wants to fight last on his journey. Shanks’ full fighting potential hasn’t been explored yet but there is a lot of hints that indicates Shanks is an extremely powerful individual. For starters, he was able to scare off a massive Sea King just by staring at it (until we figured out he used Conquerors Haki: the strongest form of Haki). He also clashed evenly with Whitebeard, a fellow Emperor and even fought another, Kaido, and arrived at Marineford without a scratch on him. Additionally, he managed to ward off Ankinu where the savage admiral seemed a bit shocked at his presence and stopped going after Luffy after he came. Most of all, Blackbeard, who had the powers of the destructive Gura Gura no Mi Fruit and the evil Yami Yami no Mi Fruit chose not to fight Shanks saying “he is not strong enough to fight him yet”.
Shanks has mastered to full extent all 3 types of Haki. He’s the only character so far with an Haoshoku Haki that actually damaged physical things.
All that makes Shanks a force to be reckoned with and definitely one of the strongest guys in the series.